Photographic shutter apparatus



July 13, 1965 M. s. DIETZ PHOTOGRAPHIC SHUTTER APPARATUS 8 Sheets-Sheet1 Filed Sept. 8, 1960 m 02 mm NQ 0: 0E m9 Ohm JNVENTOR.

AT TORNEYS July 13, 1965 M. s. DlETZ 3,194,141

PHOTOGRAPHIC SHUTTER APPARATUS Filed Sept. 8, 1960 8 Sheets-Sheet 2ATTQRNEYS July 13, 1965 M. s. DlETZ PHOTOGRAPHIC SHUTTER APPARATUS 8Sheets-Sheet 3 Filed Sept. 8, 1960 INVENTOR.

ATTORNEYs July 13, 1965 M. s. DIETZ' PHOTOGRAPHIG SHUTTER APPARATUS 8Sheets-Sheet 4 Filed Sept. 8, 1960 ATTORNEYS y 13, 1965 M. s. DIETZ3,194,141

PHOTOGRAPHIC SHUTTER APPARATUS Filed Sept. a. 1:360 s Sheets-Sheet sJNVENTOR. wax/ 1211: m 411%,

ATTORNEYS July 13, 1965 M. s. DIETZ 3,194,141

PHOTOGRAPHIC SHUTTER APPARATUS Filed Sept. 8, 1960 s Sheets-Sheet eINVE{VTOR.

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ATTORNEYS July 13, 1965 M s. DlETZ 3,194,141

PHOTOGRAPHIC SHUTTER APPARATUS Filed Sept. 8, 1960 8 Sheets-Sheet 7INVENTOR. fi ggwzv J. 0&2; M

ATTORNEYS y 13, 5 M. s. DIETZ 3,194,141

PHOTOGRAPHIC SHUTTER APPARATUS Filed Sept. 8, 1960 s Sheets-Sheet s F iG. H

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ATTORNEYS United States Patent 3,194,141 PHOTOGRAPHHC SHUTTER APPARATUSMilton S. Dietz, Cambridge, Mass, assignor to Polaroid Corporation,Cambridge, Mass a corporation of Delaware Filed Sept. 8, 1960, Ser. No.54,765 3 Claims. (Cl. 95-54) This invention relates to photography andmore particularly to improved exposure control devices.

A principal object of the present invention is to provide a shuttermechanism having an improved regulating means for controlling both theaperture defining function of diaphragm rneans of the shutter and thetime interval between initiation and termination of exposure. Otherobjects of the invention are to provide a new and improved shutterdevice of the type described wherein both expo-sure aperture andexposure time interval are determined in accordance with the intensityof illumination of the field of view of the mechanism as determined byphotoelectric means; to provide in a shutter device of the typedescribed a novel flash synchronizing mech nism; and to provide in ashutter of the type described a novel bulb exposure setting mecahnism.

Other objects of the invention will in part be obvious and will in pantappear herein-after.

The invention accordingly comprises the apparatus possessing theconstruction, combination of elements and arrangement of parts which areexemplified in the following detailed disclosure, and the scope of theapplication of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic, rear elevati-o'nal view of a shutterassembly embodying the present invention, the front housing beingremoved and the shutter being viewed from the side normally facing theexposure plane of a camera, the various parts of the shutter being shownin rest position; i

FIG. 2 is a diagrammatic, rear elevation-a1 view showing the variousparts of the shutter of FIG. 1 in a Set position;

FIG. 3 is a diagrammatic view of the shutter of FIG. 1, showing theposition ofparts during bulb exposure;

FIG. 4 is a diagrammatic view of particular parts of FIG. 1,particularly the diaphragm elements, showing their position duringexposure;

FIG. 5 is a diagrammatic view of other parts of FIG. 1, particularly alatching device for retaining the parts of the shutter in set position;

FIG. 6 is a diagrammatic, front elevational view of the shutter assemblyof FIG. 1, showing the parts in rest position;

FIG. 7 is a diagrammatic view showing the parts of the shutter of FIG. 6in set position;

FIG. 8 is a diagrammatic view showing the position of parts of theshutter of FIG. 6 during bulb exposure;

PEG. 9 is a diagrammatic view of particular elements of the shutter ofFIG. 6, showing an indicating means cooperating therewith;

FIG. 10 is a diagrammatic, rear elevationalview of part of a shutterhousing adapted to enclose the embodiment of the invention as shown inFIG. 6 and hav ing elements cooperating therewith; and

FIG. 11 is an end view partly in fragment of the embodiment of FIG. 10.

The present invention comprehends a novel shutter mechanism whichincludes a pair of solid shutter blades adapted for covering anduncovering an exposure aperture. In order to effect exposure, one of theshutter Patented July 13, 1965 ice elements is positioned in a coveringrelation to the exposure aperture and is movable to an uncoveringposition at one side of the apeuture. The other of the shutter blades isnormally positioned to one side of the aperture and is movable therefromto a covering position with respect to the aperture for terminatingexposure therethrough. The invention also includes movable diaphragmmeans for defining a variable etfective exposure aperture. The operationof the shutter blades and the diaphragm means is coupled through aregulating means which controls the timing of the sequential movement ofthe shutter blades as well as the setting of the diaphragm means therebyestablishing a system of predetermined exposure values.

In the embodiment shown, the exposure provided by the regulating meansis a function of ambient illumination. Therefore, the inventioncomprises means for rendering the intensity of the illumination in termsof mechanical displacements which are employed for predetermining theexposure parameters. The regulating means includes a bellows device, thetime rate of distortion of which governs the movement of a cam which, inturn, controls the sequential movemnet of the blades.

Referring now to the drawing, there is shown, particularly in FIG. 1,one embodiment of the invention wherein foundation means, such assubstantially planar support plate 2t), are provided for mounting theoperative elements of the invention. Plate 20 includes therein anexposure aperture or opening 22 through which it is intended toselectively pass actinic radiation to effect exposure when the inventionis employed in conjunction with a camera including photosensitivematerial such as a well-known silver halide emulsion film,thermograp'hic plate, photopolymerizable sheet, xerographic plate, orthe like. Plate 29 is formed of a material which is substantially opaqueto the radiation with which the invention is intended to be employed.Mounting upon one surface 24 of plate 2% adjacent opening 22 are shutterblade 26 and second shutter blade 28.

Blade 26 is shaped as a substantially planar elongated member includinga radiation opaque, solid covering portion 32 adjacent one extremitythereof, the covering portion being dimensioned for fully coveringopening 22 when the plane of the covering portion is alignedsubstantially perpendicularly to an optical axis through the opening andpredeterminedly positioned with respect to opening 22. Blade 26is'pivotally mounted intermediate its extremities upon suitable mountingmeans such as elongated post 3%. When so mounted, the opposite extremityof blade 26, comprising arm 34, extends radially from the postan-gul-arly with respect to a radius from the post through approximatelythe center of covering portion 32. Post 30 is mounted upon and extendsthrough plate 2% to the opposite side or surface 36 of the plate (asshown in FIG. 6), and is freely rotatable about its longaxis withrespect to the plate. Blade 26 is mounted upon post 3%] by knownoverrunning clutch means so that the rotation of the post in onedirection engages and rotates the blade in said one direction, but thepost is free to move in the opposite direction without then rotating theblade. 7

Blade 28 is also an elongated member provided with a similarlydimensioned and formed covering portion 38 adjacent one extremity. Theopposite extremity of blade 28 is bifurcated to comprise arms 40 and 42disposed at an angle to one another. Blade 28 is rotatably mounted uponpost 30 intermediate the latter two arms and covering portion 38 so thatthe arms extend substantially radially from the post. In like manner toblade 26, blade 28 is mounted at one extremity of post 3% by overrunningclutch means as described hereinbeforef The two blades are thereforerotatable in their own planes 3 closely adjacent and substantiallyparallel to one another.

Blade 26 is normally mounted so that covering portion 32 is aligned withopening 22 to completely cover the latter, being therefore in a first orclosed position as shown in FIG. 2. The blade is rotatable between theclosed position and in uncovering position wherein it is disposed to oneside of opening 22 and completely uncovers the latter (as shown in FIGS.1 and 3). Blade 28 is normally mounted in uncovering position relativeto opening 22 at one side thereof (as shown in FIG. 2) and is rotatablebetween this uncovering position and a second or covering positionwherein it is in alignment with and covers opening 22 (as shown in FIG.1).

As a means for moving blade 26 from closed position to its uncoveringposition, there is provided a resilient el ment such as elongated spring4-4 which is attached at one of its ends to appropriate mounting meansas on plate 259, and at its other end at a location adjacent the radialextremity of arm 34. When blade 26 is in its closed position, spring 44is under stress and provides a bias which tends to rotate blade 26 aboutthe pivotal axis provided by post 3% and into its uncovering position. Asimilar resilient means, such as elongated spring 48, is provided formoving blade 28. Spring 58 is mounted at its respective ends uponsuitable mounting means t disposed on plate 2t adjacent mounting meansto and upon a portion of arm 40. Spring 48 is under stress when blade2t; is in its uncovering position, thereby providing a bias for rotatingthe blade from its uncovering position to its covering positon. Means,such as spring mounted magnet 51 positioned in the path of movement ofblade 2'5 so as to be contactable thereby, is provided as a stopmechanism which defines the limit of motion of the blade after ituncovers aperture 22. Additionally, magnet 51 serves to limit, bymagnetic action on a magnetizable portion of the blade, any tendency ofthe blade to bounce when arrested by the magnet. Similarly, resilientmeans, such as springs 52. and 53 (which may be formed as a unitaryelement), are provided for arresting the motion of blade 23 after it hascovered aperture 22. Spring 52 is disposed in the path of movement of anextending portion 55 of blade 23 to define one limit of motion of thelatter. Spring 53 is located adjacent spring 52 so as to make frictionalcontact with the blade just before the latter strikes spring 52, therebyslowing the motion of the latter and preventing retrograde blademovement resulting from the impact of the blade with spring 52.

Referring now particularly to FIG. 4 of the drawings, there is shown adiaphragm means which forms part of the invention and is indicatedgenerally by the reference numeral 54. Diaphragm means 54 is preferablyof the double-bladed, linkage type and comprises a first or movablemaster leaf 5s and a second or movable slave leaf 5%, the leaves beingpivotally connected to one another by means such as elongated link dtl.Master leaf 5%; comprises an irregularly shaped member which issubstantially planar and includes a roughly crescent-shaped portion s2,and a pair of fingers 64 and on which extend at an angle to one anotherand in the plane of the leaf. Leaf 56 is mounted intermediate its armsand crescent-shaped portion upon pivot ill for rotation about thelatter. Slave leaf 53 comprises another irregularly shaped,approximately planar member including a similar crescent-shaped element72 and an extending finger 74, the leaf being mounted intermediate itscrescent-shaped portion and finger for rotation about pivot 76. In thepreferred embodiment, the crescent-shaped portions of the two leaves areof approximately the same dimensions, and pivots 7t) and 76 are mountedupon plate at substantially opposite sides of opening 22. Link 6t) ispivotally connected at its exremities respectively to a portion offinger 66 and to a portion of finger '74.

As a means for defining an effective exposure aperture in cooperationwith opening 22, the concave edge of crescent-shaped portion 62 ofmaster leaf 56 is provided with a shape such as notch 7 8, which in thepreferred form is V-shaped to define approximately a right angle;crescentshaped portion 72 of slave leaf 58 includes a similarly shapednotch 8%). Leaves 56 and 58 are disposed to be movable between a closedposition wherein the respective crescent-shaped portions overlap tocooperatively cover opening 22 and prevent the passage of actinicradiation therethrough, and a plurality of uncovering positions whereinnotches 78 and 8t) cooperate to define the outlines of a variableopening 82 which is disposed in symmetrical alignment about an axisperpendicular to the center of the plane of opening 22.

As a means for moving the diaphragm leaves, master leaf as includes anengagement element such as pin 84 rigidly mounted on leaf 56intermediate fingers 64 and 66, and radially displaced from pivot 70.The means for moving the leaves also includes rotatable post 86 mountedupon plate 26 so as to extend therethrough and being freely rotatablewith respect to the plate. Post 8%.? is coupled to the leaves by meanssuch as elongated lever 83, one extremity of which is firmly mountedupon post 36 for rotation therewith and the other extremity of which isnormally in releasable engagement with one side of pin 34 so thatrotation of the post in one direction moves the leaves, because of theengagement of lever 88 and pin 84, toward their closed position. Fest 86and leaves 56 and 53 are also coupled by resilient means such as hairpinspring 99, one portion of which is mounted upon lever 88 adjacent post86, and another portion of which is resiliently biased into engagementwith the opposite side of pin 84 so that rotation of the post in theopposite direction rotates the leaves toward their uncovering positions.It will therefore be seen that the mechanism thus provided comprises ameans for establishing a plurality of effective exposure apertures.Inasmuch as post 86 is coupled to opposite sides of pin 84 by lever 88and spring 9t), as forces exerted on either side of pin 84 cause masterleaf 56 to rotate about pivot 7t and as the rotation of leaf 56 istransmitted through link 60 to rotate slave leaf 58, rotation of post 86will cause the diaphragm leaves to move about their respective pivots inopposite directions to one another thereby expanding or contracting thedimensions of opening 82. As a means for limiting the rotation of masterleaf 56, the invention includes a cam follower or pin 92 which isprovided as an upstanding element or pin mounted adjacent the radialextremity of finger 64 and which is adapted to releasably engage a limitstop and cam element 93 both of which will be described hereinafter.

Regulating means are provided for controlling the total exposureprovided by the apparatus. The regulating means include setting meansfor controlling the magnitude or area of the effective exposure apertureprovided by the cooperation of notches 7S and with opening 22, andexposure interval control means for determining the exposure time duringwhich the effective exposure aperture remains uncovered.

The exposure interval control means, in the form shown for instance inFIG. 1, comprises a deformable pneumatic element such as substantiallyelastic, hollow bellows 94. The bellows is preferably shaped as anelongated structure having a first or movable extremity Q6 which isconnected directly to one end of a rotatable elongated arm 98 and ismovable therewith. The bellows also includes a second or fixed extremity1% having an opening 162 therein through which a fluid or gas may flowin and out of the interior of the bellows. In order to anchor the fixedextremity of the bellows, means are provided which include a passagewayfrom the bellows interior to a fluidflow controlling means, and in theembodiment shown, thi is formed as valve block lfld having tubularpassageway res therein (only part of which is shown in broken lines),the valve block being mounted by suitable means upon surface 24 of plate20. One end of passageway 106 connects to opening 162 in the bellows,and is preferably sealed to prevent movement of fluid other than betweenthe passageway and the bellows interior. The other end of passageway 186terminates at a planar surface of valve block 104 in an openingor valveaperture 107 which, in the form shown, is slit shaped.

For controlling the rate of movement of a fluid or gas in and out of thebellows by way of passageway 1% and valve aperture 197, and thuscontrolling the time rate of elastic deformation of the bellows, amovable valve element, such as substantially planar'valve plate 108, isprovided. The valve plate includes therein an arcuate opening 119 whichprogressively varies in width in a predetermined manner from oneextremity of opening 110 to the other. Plate 1(38 is mounted forrotation substantially in its own plane in a direction substantiallyperpendicular to the slit shape of valveaperture 107 and parallel to theplanar surface of valve block 104. The mounting of valve plate 163 issuch that upon rotation of the plate, opening 110 is movable closelyadjacent to and across valve aperture 1&7, thereby cooperating with thevalve aperture to vary the effective area of the latter through which afiuid or gaseous medium may pass. Opening 110 is so dimensioned as topermit flow through aperture 107 between a maximum rate determined bythe full area of the aperture and a minimum rate established by thelimitations upon the effective area of aperture 107 imposed by thenarrowest portion of opening 110. Other valve means known in the art maybe employed, although the particular construction shown herein ispreferred for its simplicity, lightness and ease of operation.

Means are provided so that exposure control can, be obtained by manualsetting of the regulating means. Additionally, in the form of theinvention shown, the regulating means selectively provides exposurecontrol responsively to the electrical signal output of photoelectricmeans such as photocell 112 shown for instance in FIG. '7, which outputis a function of the intensity of light incident upon the photosensitivesurface of the cell. It is understood that cell 112 may be photovoltaic,photoconductive or the like, and may include appurtenances, such asbatteries, which may be necessary to insure an electrical output. In theembodiment shown, cell 112 is of the photoconductive type and hascoupled therewith a pair of leads 114 and 116 which respectively provideelectrical connections for the cell with a battery (not shown). and agalvanometer described hereinafter. As a means for translating theelectrical signal output of the cell into mechanical displacements,there is provided (as shown in FIG. 1) an electrodynamic device suchas agalvanometer 118 having the usual rotatable coil 120, and indicatingmeans, such as needle 122, mounted upon the coil for rotation therewith.Appropriate means, such as electrical conductive leads 123 and 116(shown only in part in FIG. 7) are provided respectively for connectingthe galvanometer to the battery and for feeding the signals from thecell to the galvanometer. The latter is preferably of the wellknowntype, wherein coil 120 and needle 122 assume an angular equilibriumposition in accordance with the intensity of the electrical signalsintroduced therein. In order to compensate for variables such asdifferent film speeds of photographic film used in cameras which en ploythe invention, or variations in density of filters which may be placedacross opening 22, the invention comprises compensating means and tothis end, galvanometer 113 is mounted upon support means such asgalvanometer housing 125, which in turn is mounted upon plate 20 forrotation with respect thereto. The compensating means includes apparatusfor rotating the entire galvanometer as a unit, which apparatus is shownparticularly in FIGS. 6,7 and 8 and includes flat circular gear 124mounted coaxially upon galvanometer housing 125 so that the latter ismovable therewith,.gear 124 being positioned above surface 36 of plate20 and the backing plate.

manual contact, Element 126 includes circular gear 130 which is ailixedto element 126 for rotation coaxially therewith. Means such as a gear'train which, in the form shown, includes gears 132, 134 and 136, isprovided for transmitting rotation of element 126 to gear 124 so thatrotation of element 126 serves to rotate the entire galvanometer withrespect to plate 20. As a means for mounting the gear train there isprovided an elongated lever 13% which itself is pivotally mountedintermediate its ends and coaxially with element 126 and gear 130. Thegears which comprise the gear train are preferably mounted intermediateone. end of lever 138 and its pivotal mounting at pivot'128 such thatthe gear train is always in mesh with gear 130. Means, including spring140, are provided for rendering the means for rotating gear 124inoperative as by biasing lever 138 for rotation out of a position inwhich gear 136 of the gear train is in meshing engagement with gear 124.Spring 140 is mounted adjacent one of its ends upon plate 20 and at itsotherend to suitable anchor means 142 provided on lever 138 between itspivotal center and its other extremity. Means, including anengagementelement or pin 144 mounted adjacent the other extremity oflever 138 described in more detail hereinafter, are provided forreleasably retaining lever 138, against the bias of spring 140, in anangular position wherein the gear train is in meshing engagement withgear 124.

Needle 122 and coil 12%) of the galvanometer comprise means for movingcam element 93, the latter being mounted upon needle 122 for movementtherewith. The extent of rotation of diaphragm leaf 56 is determined'bythe allowable magnitude of motion of attached pin 92. It will be seenthat the shape of the surface of cam element 93, into engagement, withwhich pin 92 is movable, and the position of cam element 33 asdetermined by the galvanometer, both control the position of thediaphragm leaves and thus the aperture-defining relation of notches '78and with opening 22; this relation determined responsively to theposition and configuration of cam element 93 is a function of theambient illumination represented by the angular position of thegalvanometer coil and needle. The aperture control thus attained throughshaping of cam element. 93 provides a predetermined relationship,preferably log-linear, between the area of opening 82 and the intensityof ambient illumination affecting the photocell. And, because theposition of valve plate 108 is determined by the angular position of thegalvanometer coil also, it will be appreciated that the rate of elasticdeformation of the bellows is also a function of the ambientilluminationand bears a predetermined and fixed relation to the effective exposureaperture.

Inasmuch as coil and associated needle 122 are preferably mounted upondelicate precision bearings and are, therefore, sensitive to vibrationor other physical forces external to the invention which would disturbthe equilibrium position of the galvanometer elements, it is desirableto provide means for releasably retaining the galvanometer needle in astationary position at least during exposure operation of the invention.Additionally, as cam element 93 is adapted to be engaged by pin 92 forestablishing an effective exposure aperture in accordance with theequilibrium position of the galvanometer coil, it is also preferred thatmeans be provided for releasably retaining the needle in a stationaryposition, at least during the engagement of cam element and pin.

As shown,-particularly in FIGS. 1 through 4 inclusive, means forreleasably retaining the needle in substantially stationary positionincludes a substantially flat, resilient,

elongated clamping member 146. One extremity of member 146 is fixedlymounted, for instance, upon valve block 1&4 as at 148. The memberextends from its mounting with the opposite extremity thereof, which isfreely movable, normally positioned closely adjacent to andapproximately parallel with the plane of movement of valve plate 108 sothat the valve plate is ordinarily readily movable between member 146and block 1%. Clamping member 146 includes thereon a raised or camportion 154? intermediate its extremities and which extends upwardly ina direction away from block 104. The clamping member also includes,adjacent its movable extremity, opening 152, and is so positioned anddimensioned that opening 152 is in alignment with both valve aperture1&7 and a portion of arcuate opening 110 in the valve plate. Means, suchas locking lever 154, are provided for moving clamping member 146 in andout of engagement with valve plate 168, locking lever 154 being mountedupon post 156 for rotation therewith. Locking lever 154 is rotatable in(as shown in FIG. 4) and out (as shown, for instance, in FIG. 1) ofsliding engagement with cam portion 154) such that upon engagement ofthe locking lever with the cam portion, clamping member 146 isresiliently deformed into engagement with the valve plate and releasablylocks the latter between the movable extremity of the clamping memberand the valve block. Post 156 is mounted on support plate 20 so as toextend therethrough and be freely rotatable with respect to the plate.

As a means for releasably retaining cam element 93 in a positiondetermined by the angular displacement of the galvanometer needle justprior to exposure, there is provided elongated lever 158 which ispivotally mounted adjacent one extremity thereof upon pivot 169 forrotation with respect to plate 20. The unpivoted extremity of lever 158is shaped to provide a pair of separate engagement portions 162; and164-. Lever 158 is rotatable between a first position wherein engagementportion 162 of the unpivoted extremity is brought into engagement with aportion of cam element 93, thereby arresting movement of the latter byclamping it against the external periphery of the mounting ofgalvanometer 118, and a second position wherein engagement portion 162is out of engagement with cam element 93. Resilient means, such asspring 166, are provided for biasing lever 158 into its first position.In the form shown, spring ass is connected at one of its ends to an arm168 forming a portion of lever 158 and extending radially of pivot 161)at an angle to the axis of elongation of lever The other end of spring166 is mounted upon post 170 which, in turn, is mounted upon surface 24of plate 26 so as to extend upwardly therefrom and into the path ofmovement of a portion of lever 1S8, thereby providing a limit stop whichdefines the second position of lever 158. Lever 158 is so dimensionedthat second engagement portion 164 of the unpivoted extremity of thelever extends into the path of movement of and is adapted to engage pin92 on diaphragm leaf 56. It will be seen that the arrangement of partsprovides that the engagement of locking lever 154 with cam portion 150for arresting motion of valve plate 168, and the clamping of cam element93 for arresting the motion of the latter, result at substantially thesame time, thereby obviating any undue strain upon the mounting of thegalvanometer needle and coil which might occur in the event the valveplate and cam element 93 were arrested at different times.

The exposure interval control means also includes timing means such aselement 172 which is mounted, as shown particularly in FIGS. 1, 2 and 3,coaxially with rotatable arm 98, for rotation about suitable mountingmeans such as post 174, the latter being disposed on plate so as toextend therethrough and be freely rotatable about its long axis relativeto the plate. Rotatable arm 98 and element 1'72 are connected with post17 1 for rotation both with and independently of one another. Themounting of arm 93 and element 172 upon post 17 1 is by knownoverrunning clutch means (not shown) such that rotation of post 174 in aclockwise direction, as viewed for instance in FIG. 6, moves both arm 98and element 172 in a clockwise direction, yet post 174 is free to movein a counterclockwise direction without accompanying rotation of the armand element. The unpivoted extremity of arm 93 is directly affixed tomovable extremity 96 of the bellows. As a means for rotating arm 93 in acounterclockwise direction against retarding effect of the bellows,there is provided a resilient element, such as elongated spring 176, oneend of which is anchored to offset finger 17 8 forming a portion of arm179 which extends substantially radially of post 174 and at apredetermined angle with respect to a radius joining post 174r withmovable extremity of the bellows. The other end of spring 176 isconnected to anchoring device so that spring 176 biases rotatable arm 98against, in the form shown, the retarding effect of bellows deformationin expansion.

Timing element 172 is shaped to include a pair of limbs 18%? and 182which extend at an angle with respect to one another, the element beingmounted upon post 174 at approximately the juncture of the limbs. At itsradial extremity, one limb is provided with an extending cam surface134. In the embodiment shown in the drawing surface 134 is shaped in asimple curve of predeterminedly limited angular magnitude and having aconstant radius of curvature, the center of curvature being the post174. Timing element 172 is biased for rotation about post 174 byresillient means, such as hair spring 186, in a direction opposite tothe rotational bias exerted on rotatable arm 98 by spring 176. Arm 93 isprovided intermediate its extremities with an upstanding portion 138which extends into the path of rotation of a portion of limb 182, thelatter being biased by spring 186 into engagement with upstandingportion 188.

Rotatable arm 98 is pivotable under the bias of spring 176 from a firstposition wherein the spring is stressed to provide maximum tension andbellows $4 is in a collapsed position in which its interior space is ata predetermined minimum, to a second position wherein the bellows hasexpanded to its fullest extent and permits of no further rotation of arm98. Because of the location of upstanding portion 188 and its engagementwith limb 182, it will be seen that rotation of arm 98 from its first toits second positions is positively accompanied by rotation of timingelement 172 in the same direction. Consequently, the speed of movementof the timing element in this direction is largely governed by the speedof movement of the arm from its first to its second position, and thespeed of movement of the latter is variable in accordance with the flowof fluid into the bellows as determined by the position of valve plate1%.

As a means for releasably retaining the rotatable arm in its firstposition, it is provided with an engageable portion or pin 1% which ismounted upon an extending portion 192 of arm 9'8 upon an opposite sideof post 17d. The means for releasably retaining arm in its firstposition also include latching device 1% mounted upon pivot 1% forrotation therewith and in and out of engagement with pin 1%. Pivot 1%,in turn, is mounted upon plate 24? and extends therethrough, beingfreely rotatable with respect to the plate.

Second arm 42 of shutter blade 28 is provided adjacent its radialextremity with a cam follower or stud 1% which extends substantiallyperpendicularly to the plane of the blade. Stud 1% is so located on arm42 that under predetermined conditions (when rotatable arm 98 is in itsfirst position, timing element 172 is in its normal position whereinspring 136 has forced limb 182 into engagement with upstanding portion138, and shutter blade 28 is in its fully uncovering position), stud 1%is in slidable engagement with surface 184 of the timing element. Itwill therefore be seen that stud 19% and cam surface 18 constitute meansfor releasably retaining shutter blade 23 in its uncovering position.

Similarly, shutter blade 26 is provided intermediate post 30 andcovering portion 32 with a cam follower or stud 200 which extendssubstantially perpendicularly to the plane of the blade. Stud 2&0 is solocated on the blade that under certain conditions (when the timingelement is in its normal position, rotatable arm 98 is in its firstposition, and blade 26 is in its closed position), stud 200 is also inslidable engagement with surface 184. The latter surface and stud 200therefore constitute means for releasably retaining shutter blade 26 inits closed position.

When studs 1% and 200 are in engagement respectively with surface 184,corresponding springs 48 and 4d are stressed to exert predeterminedmaximum biases for rotating the blades. Stud 200 and surface 184 aredimensioned so as to provide for disengagement thereof following apredetermined angular rotation of the timing element as the latteraccompanies arm 98 in its movement from its first position. Followingthe disengagement of the cam surface and stud 260, it will be seen thatblade 26 is free to rotate rapidly from its closed to its uncoveringposition under the resilient bias imposed thereon.

Similarly, stud 198 and cam surface 184 are so dimensioned that after anadditional predetermined angular rotation of timing element 172, stud198 is disengaged from the cam surface to free shutter blade 28 forrotation rapidly to its fully closed position under the bias imposed byspring 48. In the preferred embodiment, the arrangement of stud 1% and200and cam surface 184 provide that upon this rotation of the timingelement, the studs are released in a sequence whereby first blade 26 isfree to move to its uncovering position, and then blade 28 is free torotate to its closed position.

From the foregoing description and the drawing, it will be apparent thata plurality of forces act upon rotatable arm 98 as it moved from itsfirst position. Because there are at least two opposed spring forces(basically, those provided by spring 176 and the inherently resilientoperation of the bellows), it is possible that some oscillation willappear during this movement of arm 98 and impair the time keepingqualities of the shutter mechanism which depend upon a relativelycontinuous, non-oscillatory movement of the timing element.Consequently, in the preferred embodiment, at least cam surface 134 ofelement 172 is formed of a plastic material which exhibits a rela tivelyhigh coehicient of friction relative to the material of which studs 198and20ti are formed. Additionally, because of the compliant couplingbetween the timing ele ment of arm 98, it will be seen that oscillationsof the bellows which result in clockwise motion of thearm does notnecessarily move the timing element in a clockwise direction, for thismotion of the arm merely urges the timing element clockwise through thespring connection. The small frictional retardation (which isconsiderably smaller in magnitude than the forces exerted by spring 17 6and bellows 94) thus provided by thenatures of the cam surface and studserves to retard this clockwise motion of the timing element urged bythe farm; thus the frictional effect together with the compliantcoupling between the timing element and arm provided by spring 186 (theforces exerted by spring 186 being of an order of mag: nitude onlysomewhat greater than the frictional forces) constitute a device whichminimizes or damps any undesirable oscillations of rotatable arm $3.Additionally, the spring coupling between the timing element androtatable element 172 serves another useful purpose describedhereinafter in connection with the setting of the various elements ofthe shutter mechanism.

Latching device 194, shown in detail in FIG. 5, is preferably providedas a compliant mechanism comprising a first elongated element 202pivotally mounted adjacent one of its ends upon pivot 1% and afiixed tothe latter for rotation therewith. Mounted upon element 202 adjacent theother end of the element is an irregularly shaped 10 elongated latchmember 204 which is rotatable with re,- spect to element 202 in a planesubstantially parallel with the plane of rotation of the element. Latchmember 2154 is mounted adjacent one of its extremities upon element 202and includes an upstanding portion or flange 2% located near the pivotalmounting of the member and which, by engagement with a side of element202, prevents rotation of member 204 in a clockwise direction p isforced into engagement with element 202. The opposite extremity ofmember 204 is shaped to present a plurality of serrations or notches 212and 214 which are radially displaced from one another with respect tothe pivotal mounting of the latch member. Notches 212 and 214 constitutemeansfor effecting the engagement of the latching device with pin190,and spring 208 therefore also constitutes means for rotating device 194in a direction toward engagement of the latter with pin 190. A limitstop, in the form of pin 216 is provided in the path of rotation ofmember 204 for establishing through engagement therewith the limit ofrotary motion of both element 202 and member 204 in a clockwisedirection.

The invention also includes means for actuating the various elementsheretofore described. In the form shown in FIGS. 6 through 8, theactuating means comprises a linkage system disposed on the oppositesurface 36 of plate 20 from the shutter and diaphragm means. The linkagesystem includes an element such'as elongated actuating lever 21% whichis mounted intermediate its extremi ties upon the backing plate forrotation with respect thereto about suitable bearing means 220. Theactuating lever is so mounted that one extremity thereof extends beyondI the periphery of the backing plate for manual engagement by anoperator of the mechanism, whereby the actuating lever may be rotated.The opposite extremity of the actuating lever is bifurcated to form apair of extending fingers 222 and 224- disposed at an angle with respectto one another. Means, such as spring 226, are provided for biasing theactuating lever for rotation in a clockwise direction into its restposition, spring 226 being mounted at one extremity upon boss 23extending from surface 36 36 of plate 20, and at its other extremityupon upstanding portion 230 of finger 222. p

p The linkage system also includes an element such as crank 232 having apair of oppositely extending arms 234 and 236. Crank 232 is mounted byarm 234 upon a portion of post 156. which extends through plate 20outwardly of surface 36, the post and crank being fixed for rotationwith one another. The linkage system also includes an elongated arcuatemember such as link 238. One end of link 233 is pivotally mountedadjacent an extremity of arm 236, the other end of the link beingpivotally mounted adjacent the extremity of and upon finger 224 therebycoupling link 232 with'actuating lever 218 so that rotation of thelatter is accompanied by rotation of post 156.

The linkage system also includes short elongated lever 243-0 having oneextremity thereof firmly connected to post 86 for rotation with thelatter. Lever 240 also includes an upstanding portion of tab 242.Actuating lever 218 and lever 240 are. respectively so dimensioned andlocated that tab 242 extends upwardly from lever 240 andinto the path ofrotation of lever 218 between fingers 222 and 224. Resilient means, suchas spring 244, are provided for biasing lever 240 in a clockwisedirection, the spring having its ends respectively mounted upon theopposite extremity of lever 240 and upon appropriate mounting means,such as boss 246, located on surface 36 of the plate. It will be seenthat the bias thus imposed upon lever 24% also biases post 86 so as toforce lever 38 firmly into engagement with pin 34.

Upon counterclockwise rotation (as viewed, for instance, in MG. 7) ofactuating lever 21% by an operator, the linkage system is movable fromits rest position, against the bias of spring 226 toward a second ordisplaced position. When the linkage system is in its rest position, aspreviously stated, lever 88 is forced against pin 84 and, therefore, pin92 is out of engagement with cam element 93. Additionally, when thelinkage system is in rest position, locking lever 154, which is coupledwith crank 232 through post 156, is out of engagement with cam portionb.

Crank 232 also includes another pair of arms 248 and 25d so disposed asto extend substantially oppositely to one another at opposite sides ofpost 15s. When the linkage system is in its rest position, arm 248 is sodimensioned and disposed as to extend into the path of movement of pin144 on lever 138 and is in engagement therewith, thereby providing meansfor releasably retaining lever 13% in an angular position wherein gear136 is in meshing engagement with gear 124.

The invention includes a cover blind or cap 252 which is shaped as asubstantially flat, elongated element having, at one end thereof, acovering portion 25% adapted to completely cover aperture 22 when in afirst position. Cap 252 is so pivotally mounted adjacent its other endupon pivot means 255 located on surface 36 of the backing plate, thatthe cap is rotatable, in its own plane substantially parallel andclosely adjacent to the plane of surface as, to a second position at oneside of aperture 22, thereby completely uncovering the latter. Resilientmeans, such as spring 253, are provided for biasing the cap into itsfirst position, spring 253 being formed as a hairpin spring wound aboutpivot means 256 and having a pair of ends respectively mounted upon pinsass and 262. In turn, pin 260 is firmly mounted upon cap 252 so as toextend into the path of movement of arm 250 for releasable engagementwith the latter following a pre determined rotation of crank 232 fromthe rest position of the linkage system. Pin 262 is firmly mounted uponsurface 36 of the backing plate and extends into the path of movement ofthe cap so that the latter is normally biased into engagement therewithby spring 258. It will therefore be seen that pin 262 constitutes limitstop means for defining the first position of the cap. Cap 252 alsoincludes second pin 263 firmly mounted thereon and extendingsubstantially perpendicularly of the plane of rotation or the cap from alocation intermediate covering portion 254- and pivot means 256.

Cooking means are provided for setting portions of the mechanism and forstressing the various springs. In the form shown, for instance, in FIG.7, the cocking means comprises cocking lever 264 which is shaped as anarcuate, elongated element having one extremity 266 pivotally mountedupon surface 36 of plate by suitable pivot means or post 268, and beingso disposed that the other extremity 2'70 of the cocking lever extendsoutwardly beyond the periphery of plate 281 for ready manual engagementby an operator of the device. Post 26% extends through plate 29 to theopposite surface thereof and is free to rotate with respect to theplate. Pivotally mounted by suitable means 272 upon an intermediateportion of cooking lever 264, and movable therewith, is one extremity ofan elongated element such as connecting link 274, the other extremity ofconnecting link 274 is pivotally coupled, as by pin 276, to one end ofan elongated element or trip lever 273. The latter is mountedintermediate its ends upon a portion of post 39 which extends outwardlyof plate 20 at surface 36 and is firmly connected thereto for rotationtherewith. Trip lever 278 includes thereon a pair of engagement portions28% and 2S2, the former being located to one side of the pivotalmounting of the trip lever and adjacent pin 276, the latter beingmounted intermediate post 3t? and the opposite extrernity of the triplever. Both engagement portions are so spaced with respect to post 3%that, upon a predetermined rotation of the trip lever in acounterclockwise direction, engagement portion 28% contacts boss 2% toarrest rotation, and upon predetermined rotation of the trip lever in aclockwise direction engagement portion 252 contacts boss 24-6 therebyarresting rotation of the trip lever in this direction.

T e mechanism provided by cocking lever 26%, link 274, and trip lever278 comprises hoisting means whereby "static-n (in a counterclockwisedirection as viewed, for instance, in FIG. 7) of lever 264 by anoperator rotates post 3'9 in a direction which allows the overrunningclutch means of post 330 to pick up both blades 26 and 23 and therebyraise both the former from its uncovering to its closed position and thelatter from its covering to its uncovering position relative to opening22. Cooking lever is rotatable between a rest and a displaced position,the rest position being defined by the arrest of movement or" thehoisting means consequent upon contact of engagement portion 22 withboss 246. Cooking lever 264 is biased into this rest position byresilient means, such as elongated spring 284, mounted upon trip lever278 and acting upon the cocking lever through connecting link 274. Queend of spring ass is preferably connected to the trip lever at alocation adjacent engagement portion 282, the other end of the springbeing mounted upon anchor pin i136 extending outwardly from surface 3-!of plate 26. The displaced position of cocking lever 264 is thereforedefined by the position at which the rotation of the trip lever, againstthe bias of spring 234, is arrested by the engagement of portion 28%with boss 246.

The cocking means also includes means for moving rotatable arm 3 and,therefore, timing element 172 from the second to the first position ofthe former. This lastnamed means comprises an elongated member 288fixedly mounted intermediate its extremities upon post 174 for rotationtherewith. One extremity of member 288 is pivotally connected, as bypivot 2%, to an intermediate portion of link 274. The other extremity ofmember 238 includes an engagement portion or downturned tab 292 thereon.Mounted firmly upon member 23% for rotation therewith are means, such assubstantially planar blade 2%, for covering and uncovering thephotosensitive portion of the photocell in a predetermined manner. Bladeis formed of material which is substantially opaque to radiationintended to be employed for exciting the photocell. Of course, the bladeis so dimensioned and photocell 112 and pivot 174 are so located thatrotation of member 288 moves the blade in and out of covering relationto the photosensitive portion of the photocell.

Latch means are provided for releasably locking the entire cocking meansinto set position wherein cocking lever 274 is in its displacedposition, blades 26 and 28 have been raised respectively to theircovering position of the former and the uncovering position of thelatter, and rotatable arm 98 and timing element 172 are in their firstposition. This latch means comprises bell crank 2% which includes a pairof extending arms 228 and Bell crank 2% is mounted at the juncture ofarms 29% and 3% upon pivot 3-22 for rotation with respect to surface 36of plate 2t). Pivot 3t2 is so located and bell crank 2% is sodimensioned that the unpivoted extremity of arm 2% extends into the pathof rotation of pin 263 and is engagebale therewith, and notched portionadjacent the unpivoted extremity of arm sea extends into and isreleasably engageable with tab 2% of member 25-38. Means, such ashairpin spring 3%, are provided for biasing bell crank 2% for rotationin a direction toward a position wherein notch portion 3% engages tab 2%and another position wherein arm 2% engages pin 263.

The invention includes means for releasing latching device 194 fromengagement with pin 1%, and this means is provided as short elongatedlever 33%. One end of lever 3% is mounted upon pivot 1% for rotationtherewith, the other end 309 of lever 308 being shaped to present anupstanding portion 310 which extends into the path of rotation of and isengageable with engagement portion 312 of trip lever 278, engagementportion 312 being located adjacent the extremity of the trip lever whichextends approximately radially of post 30 in a direction opposite to theextremity of the trip lever upon which pin 276 is mounted.

- The parts of the invention thus far described operate in the followingmanner, assuming the parts to be cocked: Electrical signals are producedby photocell 112 responsively to the intensity of the radiation intendedto be passed through exposure aperture 22 to effect an exposure. Thesignals are transmitted through leads 116, 114 and 123 to galvanometer118, and in response to the signals, coil 120 assumes a position ofequilibrium, needle 122 being moved correspondingly with the coil. Themovement of needle 122 rotates valve plate 108 so that opening 110 ispivoted acrossvalve aperture 106, thereby providing an effective areafor the passage of a fluid or gas through the valve aperture. The sizeof the effective area thus provided will be seen to be a function of themagnitude of radiation which stimulates the photocell.

Cam element 93 likewise moves with needle 122 to a.

position corresponding to the equilibrium position of the galvanometercoil.

In order to actuate the mechanism, the operator grasps an extremity ofactuating lever 218 and, by excrtingpres sure thereagainst, rotates theactuating lever in a counterclockwise direction, as shown in FIG. 6,about bearing means 220. As lever 218 is so rotated, finger 222 engagestab 242 thereby rotating lever 240 against the bias of link 60 forrotation in opposite directions, are impelled to move from their closedposition with respect to opening 22 by the force exerted on pin 84 byspring 90. This movement of the leaves is arrested by the engagement ofpin 92 wit-h clamped cam element 93 at a position determined by theconfiguration and location of cam element 93. Thus the magnitude of theeffective exposure aperture defined by the cooperation of opening 22with notches 78 and 80 is a function of the position and shape of camelement 93, and the effective exposure aperture is automaticallypredetermined in accordance with the intensity of illumination incidenton photocell 112.

Assuming that the shutter is in set position (blade 26 is in its closedposition, blade 28 is in its uncovering position, bellows 94 iscollapsed, cam surface 184 of timing element 172 is in engagement withstuds 198 and 200,

spring 244. Because of the linkage system, the rotation of lever 240 isaccompanied by the rotation of crank 232.

Thus, the initial rotation of the actuating lever, by rotating lever 240and crank 232, causes posts 86 and 156 to rotate also. The rotation ofthe latter, in turn, rotates lever 88 and locking lever 154 so that thelatter is brought into engagement with cam portion 150; the rotation ofpost 86 forces spring 90 against pin 84 i-mpelling pin 92 against camelement 93. Inasmuch as pin 92 is normally in engagement with secondengagement portion *164 of lever 158 and thereby releasably retainslever 158 in its second position, the rotation of leaf 156 under theforce exerted upon pin 84 by spring90, releases lever 158 for movementof the latter under the bias of spring portion of the galvanometerhousing. In the preferred embodiment the arrangement of parts is suchthat upon a predetermined rotation of actuating lever 218, the camrningeffect of locking lever 154 (which locks valve plate 108) and thelocking effect of lever 158 (which clamps cam element 93) are obtainedin a substantially simultaneous manner. As a consequence of theaforementioned camming and locking effects, it will be seen that needle122 and coil 120 are releasably retained in a substantially stationaryposition which is determined by the signalsreceived by the galvanometerapproximately at the time of the initial rotation of lever 218 by theoperat-or.

As the locking of the galvanometer coil occurs, the rotation of crank232 moves arm 248 away from the position at which the latter acts toreleasably retain lever 138 through engagement with pin 144, in itsposition wherein gear 136 is in engagement with gear 118. This allowslever 138 to so rotate under the impetus provided by spring 140 as todisconnect the gear train from the galvanometer housing, thus providingmeans for preventing inadvertent rotation of the galvanometer housingduring operation of the invention. It will be apparent that rotationofthe galvanometer housing, while the coil is clamped, would severelydamage the delicate bearings of notch 214 is in engagement with pin 190,and the cocking means is latched so that lever 270 is in displacedposition), instantaneous? exposure by the invention is effected in thefollowing manner. Following clamping of the galvanometer, disconnectionof the gear train and setting of the effective exposure aperture,continued rotation of actuating lever 218 moves arm 250 into engagementwith pin 260 thereby pivoting cap 252 towards its uncovering position.Approximately as cap 252 arrives at its uncovering position, pin 263engages arm 298 causing bell crank 296 to rotate against the bias ofspring 306 in a clockwise direction. This releases tab 292 from itsengagement with notch port-ion 304 of arm 300 thereby allowing movementof the cocking means under the impetus provided by spring 284. Rotationof trip lever 278 is therefore transmitted through link 274 to cockinglever 264, rotating the latter toward its rest position. The rotation oftrip lever 278 is also transmitted through link 274 .to member 288 whichpivots to move blade 294 to its covering position with respect tophotocell 112, thereby rendering the latter inoperative. As the rotationof trip lever 278 continues, engagement portion 312 thereon contactsupstanding portion 310 of lever 308 causing post 196 to rotate in aclockwise direction as viewed, for instance, in FIG. 6. The movement ofthe various elements of the cocking means continues until they havearrived at under the bias imposed by spring 176. The rotation of arm 98and timing element 172 tends to expand bellows 94 from its collapsedposition thereby causing an attenuation of the working fluid in thebellows and creating a retarding force acting against the rotating biasof spring 176. The retarding force exerted by the bellows is establishedby the rate of flow of the working fiuid into the bellows, which rate isa function of the effective aperture provided by the combination ofopening and valve aperture 107 in accordance with equilibrium positionof the galvanometer coil. Consequently, the speed of rotation of arm 98and timing element 172 is controlled in accordance with the electricalsignals produced responsively to light incident upon the photocell atapproximately the time that the galvanometer mechanism was clamped. Astiming element 172 rotates from its first position, surface 184 movesrelative to studs 198 and 280, releasing stud 200 after a predeterminedrotation and after an additional rotation, releasing stud 198.

With the release of stud 200, shutter blade 26 rotates rapidly from itsclosed position (as shown in FIG. 2) toward its open position (as shownin FIG. 3) under the impetus provided by spring 44, thereby initiatingexposure through the effective exposure aperture provided by the 1.5cooperation of the diaphragm leaves and opening 22. This rotation ofblade 26 continues until arrested by engagement thereof with magnet 51.

Upon the release of stud 198, shutter blade 28 is rotated rapidly underthe bias of spring 43 from its open position (as shown in FIG. 2) towardits closed position (as shown in FIG. 1), thereby abruptly terminatingthe exposure. The timing interval of the exposure provided by themovement of the shutter blades is thus determined by the speed ofrotation of timing element 172 between the sequential release of therespective studs, and, consequently, is a function of the level ofambient illumina tion determined by the photocell.

Following rotation of actuating lever 218, in a counterclockwisedirection, which effects exposure, release of the actuating lever by theoperator permits return of lever 218 in the opposite direction under thebias of spring 226. This then releases the engagement of finger 222 withtab 242 and allows spring 24 4 to rotate lever 24%), thereby restoringthe diaphragm leaves to their closed position and permitting lever torotate out of engagement with cam element 93. Also, as a consequence ofthe return movement of lever 218, crank 232 is rotated in a clockwisedirection forcing lever 138 to rotate until gear res is again reengagedin mesh with gear 124. This rotation of crank 232 also moves arm 25% outof engagement with pin Zdtl and permits cam 252 to return, under thebias of spring 253, to its closed position with respect to opening 22.The return of cap 252 to its closed position also permits theaccompanying rotation therewith of bell crank 295 under the bias ofspring 3%. With the arrival of cap 252 in its closed position, therotation of the bell crank is arrested by virtue of the continuingengagement of arm 298 with pin 2-63 and the bell crank is in a positionof arrest wherein notch 3114 is adjacent but not in engagement with tab292.

In order to cock or set the mechanism, extremity 27 of cocking lever 26-is grasped by an operator and rotated in a counterclockwise direction,as viewed in FIG. 6. The rotation of the cocking lever is transmittedthrough link 274 to simultaneously rotate member 238 and trip lever 278,thereby moving blade 294 out of covering relation to the photocell (andrendering the latter operative) and rotating posts 1'74 and 36. Thecounterclockwise rotation of member'288 causes tab 292 to engage aportion of arm 3%, rotating bell crank 2% until tab 222 slips intoreleasable engagement with notch portion 3% of arm 3% and restrains thehoisting means from movement in an opposite direction until notchportion 3% is disengaged from tab 292, as hereinbefore described. Therotation of post 3t? picks up blades 26 and 28, moving them respectivelyto set position. The simultaneous rotation of post 174 moves rotatablearm 98 against the bias of spring 176, compressing bellows 94 androtating timing element 172 so that a side of limb 18f) engages pin 198.The engagement of pin 198 with limb 18d arrests the rotation of thetiming element, camming the latter into a retrograde movement againstits resilient mounting upon arm 98 until stud 198 slips past the radialextremity of limb 1% and, accompanied by stud 2%, onto cam surface 184for engagement therewith. It will therefore be seen that the springcoupling provided by spring 186 between arm 98 and the timing elementconstitutes means for permitting variation of the angular relationbetween the arm and timing element during engagement of pin 198 with aside of limb 18d.

As trip lever 278 is rotated in a counterclockwise direction, as viewedin FIG. 6, engagement portion 312 disengages upstanding portion 311? oflever 31% thereby permitting latching device 194 to rotate in aclockwise direction (as viewed in FIG. 5) into engagement with pin 1% ata position intermediate flange 2% and notch 212. As arm @3 is rotatedwith the rotation of post 1'74, pin 1% is carried in sliding engagementwith latching device 194 along the margin of the latching device,exerting a force thereagainst which rotates latch member 2% with respectto element 2&2 against the compliant mounting provided by spring 2%,thereby allowing pin 1% to slide along the margin of latch member 2%until engagement with notch 214. The latter engagemerit acts toreleasably retain arm 98 in its first position and, therefore,releasably retains the shutter in its set position.

The present invention also includes means for providing bulb exposures,and in the embodiment shown, comprises elongated bulb lever 314 which isso mounted upon surface as intermediate its extremities that a portionthereof extends outwardly of the periphery of plate 2t? so as to bemanually engageable by an operator of me device. The opposite extremityof bulb lever 514 includes an engageable portion 316 which is rotatableinto engagement with a portion of end 369 of lever 3% for rotating thelatter a predetermined distance about post 1% against the bias of spring2268. Bulb lever 314 is rotatable between an inoperative positionwherein engagement portion 316 is out of engagement with end 3% and anoperative position wherein engagement portion 316 has engaged end W9 androtated lever 308 the requisite amount.

When bulb lever 314 is in its operative position (as in FIG. 8), thedistance which post 196 is rotated moves latching device 1% to a newposition which narrows the magnitude of movement of device 194 in acounterclockwise direction. Hence, upon actuation of the shutter, themotion of latching device 194 is sufficient to break the engagement ofnotch 214 with pin 1% but, being then arrested at the new position,cannot move enough to rotate notch 212 out of the path of movement ofpin 1%, thus the pin is engaged by notch 212. Consequently, rotatablearm 93 moves only sumciently to release stud Ztli). This permits blade26 to move from its closed position toward its open position. However,stud 198, remaining in contact with cam surface 184 because of theengagement of pin 1% with notch 212, retains shutter blade 28 in itsopen position, the position of the two blades then being as shown inFIG. 3. It will be seen that the shutter blades under thesecircumstances provide no cover for aperture 22. And, as long as anoperator of the device maintains pressure against actuating lever 218,cap 252 is held to one side of aperture 22 and the diaphragm blades aremaintained in their open position. Thus the total exposure time is con.-trolled at the discretion of the operator.

After bulb exposure has been effected, the return by the operator ofbulb lever 314 to its inoperative position permits the operator to resetthe mechanism by manipulation of cooking lever 264 so as to eifectinstantaneous exposures thereafter. Means, such as spring 3118 connectedto an intermediate portion of bulb lever 314 and to plate 20, areprovided for biasing the bulb lever into operative or inoperativeposition, thereby insuring that the bulb lever will not inadvertently beplaced in an intermediate position.

The present invention also includes means for synchronizing theoperation of the shutter with well-known photographic flash devices forproviding supplementary exposure illumination.

In the preferred embodiment, particularly as shown, for instance, inFIG. 2, the means for synchronizing the operation of the shuttercomprises a pair of switching devices, one for use with the so-calledvaporizable type of flash unit, such as is shown in U.S. Patent No.2,812,420 issued November 5, 1957 to H. A. Bing et a1., and the otherfor use with well-known stroboscopic flash unit, such as shown in U.S.Patent No. 2,824,953 issued February 27, 1956 to K. C. Rock, neither theunits nor the external circuitry thereof being shown to avoid undulycomplicating the drawing.

One switching device for use with a stroboscopic flash unit comprises aconnecting or contact means such as resilient contact 320 adapted to beengageable by one contact of the usual stroboscopie unit jack (notshown), contact 320 being mounted upon plate 20 and electricallyinsulated therefrom. Contact 320 is electrically connected by lead 322to first switch contact 324. The latter is mounted upon plate 20 so asto be electrically insulated therefrom and comprises a resilient,electrically conductive element disposed in the path of rotation of .aportion of arm 40 of blade 28. Arm 40 is preferably formed of anelectrically conductive substance grounded to plate 20 as through post30 and, therefore, constitutes a switch contact. As known in the art,the other contact of the jack of the stroboscopic flash unit also isgrounded to plate 23. Switch contact 324 and arm 40 are so disposedrelative to one another as to be out of engagement whenever blade 28 isin covering position relative to aperture 22. When blade 28, uponrotation thereof, arrives at its uncovering position with respect toaperture 22, arm 40 engages switch contact 324 thereby actuating thestroboscopic flash unit. Because switch contact 324 is in the path ofrotation of arm 40, it is also in the path of rotation of arm 34 ofblade 26 and is normally out of engagement with arm 34 whenever blade 26is in uncovering position relative to the exposure aperture. Blade 26includes thereon an engagement element 326 adapted to engage contact 324as blade 26 moves to covering position, thereby moving contact 324 outof engagement with arm 4%. Engagement element 326 is electricallyinsulated from blade 26. It will therefore be seen that upon actuationof the shutter for exposure, the stroboscopic flash unit is activatedimmediately as exposure commences, i.e., as soon as blade 28 hasuncovered aperture 22. The exposure interval, therefore, obtained by useof the stroboscopic flash unit is determined by the duration of theflash rather than by the timing of the shutter mechanism. Immediatelyupon termination of exposure, the flash contacts are opened so as toprevent undue drain upon the stroboscopic flash unit.

The other switching device comprises a two element switch including astationary switch contact, such as pin 328, mounted upon plate 20 andelectrically connected thereto. Also included is a movable contact 330which is mounted upon plate 20 for rotation with respect thereto and isinsulated therefrom, contact 330 being rotatable in and out ofengagement with pin 328. I Resilient means such as spring 332 areprovided for biasing contact 330 toward engagement with pin 328. Aportion of contact 330 is also located in the path of movement of pin333 which is disposed upon arm 179, pin 333 being formed of anelectrically insulating material so that no electrical connection isformed by its engagement with contact 330. The partsthus far describedare so disposed that when rotatable arm 98 is in its first position andthe shutter mechanism is, therefore, in set position, contact 330 and328 are retained out of engagement with one another through theengagement of pin 333 with contact 330. Following actuation of theshutter mechanism, stud 200 is released from cam surface 184 to initiateexposure, and the rotation of arm 98 by which this is accomplishedrotates arm 179, allowing contact 330 to move toward pin 328 under thebias of spring 332. At a pretermined rotation before the timing elementhas rotated sufiiciently to disengage stud 198 from cam surface 184, arm179 has rotated sufiiciently to allow the switch contacts to close andthus actuate the usual vaporizable type of flash unit. The flashsynchronization provided by this switch device is a function of theshutter timing because continued rotation of the timing elementfollowing the switch closure releases stud 198 and allows thetermination of exposure by the closure of blade 28.

Safety means are provided in connection with the latter switching devicein order to maintain an open circuit except during shutter actuation,thereby preventing premature discharge through the flash bulb, filament.To this end, the shutter is provided with lead 334 electricallyconnected to contact 330 and to one side, such as first switch element336, of a supplementary switch shown, for instance, in FIG. 7. Firstswitch element 336 comprises a stationary post maintained upon surface36 of plate 20 and electrically insulated therefrom. Also mounted onplate 20 adjacent first switch element 336 and electrically insulatedfrom both the'latter and plate 20, is a resilient switch element 338.Element 338 is so disposed in the path of movement of finger 224 ofactuating lever 218 as to be engageable by an insulating portion or boss340 mounted adjacent the extremity of finger 224. Elements 338 and 336are so disposed as to be retained out of engagement with one, another byboss 340 whenever actuating lever 218 is in its rest position, element338 being free to move into contact with element 336 through the re-.siliency of the former only when boss 340 is moved consequent torotation of actuating lever 218 out of its rest position. The resilientswitch element 338 is connected by means such as lead 342 to one side ofthe standard vaporizable flash unit, the other side of the flash unitbeing, of course, grounded to plate 20 and, therefore, electricallycoupled to pin 328. It will therefore be seen that no power can flowthrough the flash unit until first, switch elements 333 and 336 areallowed to contact one another upon rotation of the actuating lever, andthen after rotatable contact 338 has moved into engagement with pin 333.

It has heretofore been noted that the invention comprises compensatingmeans for adjusting the response of the shutter for variables such asdifferent film speeds. The compensating means act to rotate the entiregalvanometer as a unit so that the position of the zero point (theno-current position of the galvanometer needle) is variable with respectto both the fixed position of valve aperture 107 and the fixed path ofmovement of pin 92 thereby comprising means for varying the relation orcoupling of the galvanometer with the exposure interval control meansand with the aperture control means. The compensating means alsocomprises means for adapting the shutter mechanism for manual operation.Thus, the invention includes a selected indicating mechanism which, inthe form shown particularly in FIGS. 9, 10 and 11, comprises indicatingelement or circular disc 344 which is mounted for rotation about pivot346 which extends through elongated support member 348. The supportmember is mounted adjacent surface 36 near galvanometer 118 upon posts350 and 352. Connected to pivot 346 for rotation therewith and with disc344 is gear 354 which is in meshing engagement with gear 124. Thusrotation of the latter is transmitted through gear 354 and pivot 346 soas to be accompanied by a corresponding rotation of disc 344.

Disc 344 includes thereon a pair of sets of indicia (numerals 355 and356 being employed to identify-exemplary members of each set), theelements of one set being arranged in circular order about the pivotalcenter of the disc, and the elements of the other set being similarlyarranged in another circle concentric with the first. One set 356 ofindicia comprises a series or arbitrary set of numerals, well known inthe art, indicative of exposure values, i.e., so-called EV numbers. Theother set 355 of indicia comprises a plurality of arbitrary numerals,also well known in the art, indicative of ASA film speeds. The indiciaof each set are arranged in a predetermined manner with respect to oneanother so that some indicia of each set lie upon substantially the sameradii with respect to the pivotal center of the disc.

Referring particularly to FIGS. 10 and 11, there will be seen, partly infragment, a covering element or front housing 357 adapted to enclose theshutter mechanism adjacent surface 36 thereof. The housing includes anopening or elongated window 358 so located as to overlie a radialportion of disc 344 when housing 357 is in covering relation to theshutter mechanism. Window 358 is provided with a slide mechanism whichincludes planar cover 360 mounted for movement in its own plane acrossthe window and dimensioned to cover substantially one half thereof.Manually engageable means, such as button 362, is connected with theslide mechanism to comprise means by which cover ass can be moved toblock either one end portion or the other of the window by manualoperation of the operator of the mechanism. The slide mechanism alsoincludes an upstanding member, such as tab 363, which extendssubstantially perpendicular to the plane of movement of the slidemechanism and, being firmly attached thereto, is movable with cover 360.

It should be noted that leads 116 and 123 to galvanometer 118 areconnected to the latter through the terminals of a switching devicewhich comprises a first or stationary contact 364 mounted upon surface36 of plate 26 and electrically insulated therefrom. The switchingdevice also includes a movable member, such as resilient contact 366,which is also mounted upon surface 36 and electrically insulatedtherefrom. Con act 364 is connected to lead 116 and contact 366, inturn, is connected to lead 123. Contact 366 is normally biased as by itsown resiliency out of engagement with contact 364 and is movable intoengagement with the latter to provide an electric network whicheffectively short circuits the galvanometer, therefore, rendering thelatter inoperative.

When housing 357 is in covering relation to the shutter mechanism,resilient contact 366 is so dispose as to extend into a portion of thepath of movement of tab 363. When the tab is in a first position whereincover 360 blocks one end of window 358, tab 363 is out of engagementwith contact 366; and when the tab is moved to a second position whereincover 360 blocks the opposite end of the window, tab 363 has been movedinto engagement with contact 366 thereby moving the latter intoengagement with contact 364, and short circuiting the galvanometer. Itwill therefore be seen that the tab and switching device comprisingcontacts 364 and 366 constitutes means for selectively rendering theshutter mechanism of the invention either manually or photoelectricallyoperative insofar as the determination of exposure values is concerned.Consequently, when the tab is in first position and contacts 364 and 366are open, the exposure values of the shutter mechanism are determinablephotoelectrically; the particular indicium disposed upon disc 344 andapparent through the unblocked portion of window 358 therefore isrepresentative of film speed, and the galvanometer is correspondinglyadjustable by rotation thereof upon manipulation of element 126 toadjust the mechanism for the speed of the photosensitive material to beemployed with the shutter. Correspondingly, when the tab is in itssecond position, the exposure values of the shutter mechanism can nolonger be established photoelectrically; and the particular indicium ondisc 344 apparent through the unblock portion 20 of the window indicatesthe exposure value which is then set according to the desires of theoperator by his manipulation of element 126 to rotate the galvanometer.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

1. A photographic exposure control mechanism comprising, in combination:means defining an exposure aperture, shutter means movable from a setposition to a rest position with respect to said aperture to effectexposures therethrough; first biasing means tending to move said shuttermeans toward said rest position; a movable member adapted, when in afirst position, to engage a portion of said shutter means and retain thelatter in said set position; a pneumatic device having a movableportion; an arm having a first portion attached to said movable portionfor movement therewith, and a second portion adapted to engage saidmovable member and move the latter away from said first position inresponse to movement of said movable portion in a first direction,whereby said movable member is moved in frictional contact with saidshutter means until the latter is released from said set position; andsecond biasing means tending to move said arm and said movable member inopposite directions, whereby when said movable portion is moving in saidfirst direction, oscillations of said pneumatic device which tend tomove said movable portion in a second direction are damped by saidsecond biasing means and said frictional contact between said movablememher and said shutter means.

2. A photographic exposure control device according to claim 1 whereinsaid pneumatic device comprises an expansible and collapsible bellows.

3. A photographic exposure control device according to claim 1 whereinsaidmovable member is mounted for rotating movement relative to saidshutter means upon a common pivotal mounting with a portion of said arm.

References Cited by the Examiner UNITED STATES PATENTS 568,102 9/96Royle 54 590,752 9/97 Cook 9560 2,800,844 7/57 Durst 95-60 2,960,01611/60 Distel 95-10 2,963,951 12/60 Wareham 95-60 2,966,102 12/60Whittier 9511.5

NORTON ANSHER, Primary Examiner.

L. W. VARNER, 111., DELBERT B. LOWE, Examiners.

1. A PHOTOGRAPHIC EXPOSURE CONTROL MECHANISM COMPRISING, IN COMBINATION:MEANS DEFINING AN EXPOSURE APERTURE, SHUTTER MEANS MOVABLE FROM A SETPOSITION TO A REST POSITION WITH RESPECT TO SAID APERTURE TO EFFECTEXPOSURES THERETHROUGH; FIRST BIASING MEANS TENDING TO MOVE SAID SHUTTERMEANS TOWARD SAID REST POSITION; A MOVABLE MEMBER ADAPTED, WHEN IN AFIRST POSITION, TO ENGAGE A PORTION OF SAID SHUTTER MEANS AND RETAIN THELATTER IN SAID SET POSITION; A PNEUMATIC DEVICE HAVING A MOVABLEPORTION; AN ARM HAVING A FIRST PORTION ATTACHED TO SAID MOVABLE PORTIONFOR MOVEMENT THEREWITH, AND A SECOND PORTION ADAPTED TO ENGAGE SAIDMOVABLE MEMBER AND MOVE THE LATTER AWAY FROM SAID FIRST POSITION INRESPONSE TO MOVEMENT OF SAID MOVABLE PORTION IN A FIRST DIRECTION,WHEREBY SAID MOVABLE MEMBER IS MOVED IN FRICTIONAL CONTACT WITH SAIDSHUTTER MEANS UNTIL THE LATTER IS RELEASED FROM SAID SET POSITION; ANDSECOND BIASING MEANS TENDING TO MOVE SAID ARM AND SAID MOVABLE MEMBER INOPPOSITE DIRECTIONS, WHEREBY WHEN SAID MOVEABLE PORTION IS MOVING INSAID FIRST DIRECTION, OSCILLATIONS OF SAID PNEUMATIC